1. Field of the Invention
The present invention relates to a mounting module of an oil control valve and, more particularly, to a mounting module on which an oil control valve for tappet control is mounted in a cylinder deactivation engine.
2. Description of Related Art
Recently, a cylinder deactivation (hereinafter, referred to as “CDA”), in which the combustion operation of specific cylinders is not made under the conditions such as a coasting drive, has been applied for the purpose of improving fuel efficiency in an automotive engine.
The CDA is directed to a method for deactivating a portion of the cylinders when stopping a vehicle or driving a vehicle at cruise speed, in which the fuel supply and the operation of intake/exhaust valves for the corresponding cylinders to be deactivated are suspended.
For example, when a driver wants to stop a vehicle of an 8-cylinder engine in a driving state, there is no reason for generating power by operating all cylinders. Accordingly, each two cylinders in four banks (two-divided cylinder block in a V-type engine) is deactivated and the engine is operated with the remaining two cylinders in the four banks, thus improving the fuel efficiency, which is directed to the CDA.
Moreover, in case of a 6-cylinder engine, three cylinders in one bank are deactivated and other remaining three cylinders in the other bank are operated.
The CDA can be also applied to a vehicle driving at cruise speed. In this case, it is characterized to generate a combustion pressure higher than that produced in the 8-cylinder combustion by increasing the fuel injection amount and the air intake amount, since it is necessary to generate a sufficient power required in the cruise drive only with four cylinders.
As such, in the CDA control mode, it is possible to reduce the fuel consumption amount since the fuel is not supplied to four cylinders in both sides, and further it is possible to attain considerably a high fuel efficiency since the power loss caused by friction does not occur in the deactivated cylinders.
The CDA includes a process of simply intercepting the fuel and a valve deactivation process. The former has a drawback in that the opening and closing operation of the valves are continuously made even if the fuel is intercepted, thus causing pumping losses through the valves.
The valve deactivation process is to stop the operation of the valves by specially modifying tappets for driving the valves or by using a device for controlling a rocker arm and, particularly, a mechanism mainly used for controlling the valves' opening and closing is directed to a method of using switching tappets.
The switching tappet is controlled by an oil control valve OCV, in which a pressure of a cam is controlled not to act on a valve by a pressure of oil supplied through the oil control valve so that the corresponding valve is not opened and closed regardless of the operation of the corresponding cam.
Meanwhile, the oil control valve for controlling the switching tappet in the CDA engine is mounted on the rear of a cylinder head. As depicted in FIG. 1, a mounting portion 11 in which the oil control valve, not depicted, is integrally molded in the rear of the cylinder head 10, and a plurality of oil passages connected to an oil path of the oil control valve is established in the mounting portion 11.
The mounting portion 11 is molded integrally with the cylinder head during the die casting process. Here, to establish the oil passages connected to the oil path of the oil control valve in the mounting portion 11, the cylinder head 10 and the mounting portion 11 are integrally molded and, then, holes are penetrated from the outside at the respective positions of the oil passages in the mounting portion 11 using a separate device.
The oil passages in the mounting portion 11 integrally molded on the rear surface of the cylinder head 10 include an oil supply passage (P-port) 12, connected to an oil inlet portion of the oil control valve, for forwarding oil supplied from a main oil gallery to the oil inlet portion of the oil control valve, an oil drain passage (T-port) 13, connected to an oil drain portion of the oil control valve, for draining an overpressure oil discharged from the oil control valve to a predetermined path in the cylinder head; and an oil exhaust passage (A-port) 14, connected to an oil outlet portion of the oil control valve, for supplying oil, i.e., an operation oil for controlling a tappet, discharged through the oil outlet portion of the oil control valve, to the tappet.
Referring to FIG. 1, in the mounting portion 11 on which the oil control valve is mounted, reference numeral 15 denotes a valve position surface on which the oil control valve is attached disposing a gasket therebetween, and two valve position surfaces 15 for mounting two oil control valves thereon are depicted.
Reference numeral 16 denotes a hole into which the oil inlet portion of the oil control valve is inserted to be connected to the oil supply passage 12 in the mounting portion 11, and reference numeral 17 denotes a bolt connection hole through which the oil control valve is fixed to the mounting portion 11.
In an example depicted in the figure, the oil control valve receives oil from a main oil gallery through the oil supply passage 12 in the mounting portion 11, and an overpressure oil in the oil control valve is drained to a predetermined path of the cylinder head 10 through the oil drain passage 13.
Moreover, the oil supplied from the oil control valve to the tappet is transmitted to the cylinder head 10 through the oil exhaust passage 14 and finally supplied to the tappet.
In such a case where two oil control valves are mounted therein, it is necessary to process holes (marked with solid line arrows in FIG. 1) eight times in total (four times only for the oil supply passage, and more than eight holes are required according to the number of the oil control valve) to establish the oil supply passage 12, the oil drain passage 13 and the oil exhaust passage 14. Such a method in which the holes are penetrated from the outside to establish the respective oil passages has the following drawbacks.
First, the die structure for the cylinder head 10 is complicated since the mounting portion 11 is molded integrally with the cylinder head 10.
Moreover, in the process of penetrating holes for establishing the respective oil passages in the mounting portion 11 after molding the mounting portion 11 integrally as described above, the holes are penetrated by inserting a tool from the outside of the mounting portion 11 thereto, the holes remain penetrated through the mounting portion 11 externally to which the tool was inserted.
Accordingly, to close up the holes exposed externally of the respective oil passages in the mounting portion 11, steel balls (not shown) are inserted into the respective holes exposed externally or taper plugs (not shown) are mounted therein as depicted in FIG. 1.
In general, the steel balls are inserted into the holes exposed externally of the oil supply passage 12 and the oil exhaust passage 14, and the taper plug is mounted on the oil drain passage 13, since it is difficult to insert the steel ball as the hole pressing direction is tilted and the hole exposed externally is close to the steel ball insertion portions of the oil supply passage 12 and the oil exhaust passage 14 as depicted in FIG. 1.
Like this, since the hole pressing direction of the oil drain passage 13 is tilted, it is necessary to use a separate hole pressing device, differently from the process of pressing the oil supply passage 12 and the oil exhaust passage 14, thus increasing the equipment cost therefor.
Moreover, since it is necessary to establish the steel balls and the taper plugs as much as the number of the oil passages, the number of parts and processes are increased and particularly an additional tool for establishing the taper plug is required separately from the equipment for establishing the steel balls.
Furthermore, it is necessary to provide a slope in the cylinder head die due to the position of the oil drain passage and thereby unnecessary mass portions are generated due to the slope of the die, thus increasing the weight thereof.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.